Adhesive applicator crayon



16, 1966 G. A. BRENNAN 3,267,052

ADHESIVE APPLICATOR CRAYON Filed April 29, 1963 INVENTOR.

United States Patent 3,267,052 ADHESIVE APPLICATOR CRAYON George AndrewBrennan, 2203 Walnut St, Philadelphia 3, Pa. Filed Apr. 29, 1963, Ser.No. 276,363 2 Claims. (Cl. 26ll-5) This application is a continuation inpart of my prior application filed March 4, 1958, Serial No. 718,997,that of February 25, 1957, Serial No. 641,855, and my pendingapplication filed July 28, 1960, Serial No. 45,820.

This invention relates to adhesive devices and to methods of applyingadhesives. More particularly, the invention pertains to implements,tools or crayons formed of special thermoplastic adhesive compositionsand to methods of applying adhesives for joining together objects, e.g.sheets of paper, without the need for heating device-s, mechanicalfastening devices or liquid adhesives.

There are a multitude of known commercially available adhesive devices,products and compositions which may be employed to adhere or fasten twosheets of paper or similar material together. In connection with suchdevices it is necessary to consider not only the shortcomings of andlimitations of various type of adhesives themselves, but to alsoconsider the deficiencies in the receptacles or containers of adhesives,applicators or combinations of container and applicator.

The adhesives heretofore available can be classified into four majorcategories, i.e., solvent activated, chemically activated, heatactivated, and pressure activated.

The solvent activated group of adhesives encompasses a wide rangeextending on one hand from gummed paper, such as postage stamps, whichare moistened just prior to use, to the common liquid glues and cementswhich are kept in solution by a solvent, and then permitted to dry toform a bond.

Gummed papers are convenient, in that they are nonliquid and require noelaborate containers or applicators but this advantage is somewhatoifset by the fact that unless a person is willing to moisten them fromthe mouth, it becomes necessary to have a water applicator, which mayhave many of the same drawbacks as an applicator of a liquid adhesive.

Liquid glues and cements are frequently sold in dispensing containers,such as flexible metal foil tubes, or plastic flasks, with nozzle typeapplicator tops, or in glass jars or metal cans with screw tops andvarious type of spreaders.

Regardless of the type of applicator used, all liquid 'ahesives have thecommon problem of evaporation of the solvent, leaving the adhesive in anunsuitable if not unusable state. Failure to promptly reclose containersaggravates this condition, and faulty closures make the conditionunavoidable.

Flexible tubse become cracked or punctured, permitting the contents toleak out, or when accidently crushed they devolep intenal pressure whichcauses the adhesive to spurt out uncontrollably when opened.

Nozzles tend to clog with hardened adhesive, which is increased whennozzle cap is lost, bent or broken.

Screw caps become coated with adhesive and are difficult to open, whilebrushes and spreaders become caked with hardened adhesive and are clumsyto use.

Many solvents used are both toxic and inflammable, and will permanentlydamage furniture finishes and synthetic fabrics.

Even water soluble glues tend to mar varnish, and cause paper and otherfibrous materials to swell, making paper wrinkle or distort.

Water soluble adhesives are impractical to remove from paper, onceapplied, often making messy joints, especially where the papers must beacurately aligned or positioned. Once a liquid coated paper is laid inplace even lightly, there is an inevitable transfer of the adhesive tothe surface on which it was laid. Frequently these liquid adhesives havea tendency to seize to the paper within seconds from the time they arebrought into contact, so that further repositioning of the papersbecomes practically impossible.

Many types of liquid glues, muscilages, and cements tend to stainthrough paper with age, or to cause dyes in the paper to run.

Obviously all adhesives stored in glass jars or bottles are subject tobreakage, and most other containers may be spilled, or when the liquidlevel becomes lowered the air space above the liquid permits evaporationof the solvent even within a tightly sealed container.

It is also a common problem that solvent liquified adhesives dry at anuncontrollable rate, and it is not generally practical to either retardor accelerate the drying time appreciably.

In the industrial field, and especially the paper laminating industry,heat sealing adhesives have become widely used to overcome theseproblems and also to achieve better bonds between foils, waxed papersand plastic film.

However, while heat sealing adhesives solve many of these problems, thecost of applicators, and sealers, with their bulk, warm up time,maintenance problems, and

other than metals.

Another class of adhesives consists of those which are permanently tackyand depend upon external pressure to achieve a bond.

These are largely limited to various types of sheetings with a precoatedsurface of a so-called pressure sensitive adhesive. Such tapes have beencoated on both sides so they may be introduced between two surfaces tobe joined. but because such tapes are generally difiicult to handle, andmay require special masking strips to prevent the bonding of such tapesto themselves, they are costly and slow to use.

Pressure sensitive adhesive tapes may be used to fasten edges oradjoining surfaces of articles or materials, but unless the tape ishighly transparent the appearance of joint may be objectionable.

Such tapes do have a great advantage over most other adhesives in thatthey can be peeled off from hard surfaces again, and thus have manytemporary uses for which liquid or other permanent adhesives would notbe suited. The tapes also have the advantage of instant adhesion.However, when applied to paper or other fragile surfaces they arediificult to remove without damage to the surface.

From the foregoing analysis of the adhesive field it is obvious that nosingle adhesive is ideally suited to all materials and uses, and thateven within the area for which it is best suited, every known adhesivehas one or more disadvantages, some of which have been enumerated above.

It is the object of the present invention to provide a new adhesive toolcapable of applying a useful pressure sensitive adhesive coatingdirectly from a non-fluid mass, the coating being easily and rapidlyapplied in either thin continuous films suitable for the temporaryjoining of thin sheet materials such as paper, foils, or plastics; orwhen desired, more adhesive deposits of a heavier nature which aresuitable for more permanent bonding of such films.

It is a further object of this invention to achieve the aforementionedobject while largely or completely avoiding each and every shortcomingpreviously discussed for all adhesives in all classifications.

Other objects and advantages of the invention will be apparent from thedescription and claims.

The nature and characteristic features of the invention will be morereadily understood from the following description, taken in connectionwith the accompanying drawings forming a part thereof, in which:

FIG. 1 is a view in elevation of an adhesive crayon in accordance withthe present invention.

FIG. 2 is a longitudinal sectional view taken approximately on the line22 of FIG. 1.

FIG. 3 is an elevation and cut away view of another ,form of thisinvention.

FIG. 4 is an elevation and cut away view of another form of thisinvention.

FIG. 5 is an elevation and cut away view of another form of thisinvention.

FIG. 6 is an elevation view of another form of this invention.

FIG. 7 is a cross sectional view of FIG. 8 taken at line 33 of FIG. 8.

FIG. 8 is an elevation of another form of this invention.

It should be understood, of course, that the description and drawingsherein are illustrative merely and that various modifications andchanges can be made in the components and their properties and in themethods disclosed, without departing from the spirit of the invention.

The invention in its broadest aspects is based upon the use in varyingproportions as hereinafter referred to, of a tack providing component orfactor, a plastisizing and tack enhancing component or factor, amark-off promoting and film spinning component or factor, a frictionalheat generating component or vfactor and a delayed hardening componentor factor. These 5 components or factors may be supplied by as few asthree materials or by five or more. But in all cases, three materialsare essential: a hard resin, a soft rubber or rubber like material, anda soft wax. Each of the three basic ingredients performs three or moreprimary and secondary functions when in the presence of the other twobasic ingredients, as will be more fully described elsewhere in thisspecification.

These components are combined in the form of a pressure sensitive,thermoplastic adhesive which is shaped into an elongated or crayon-likebody. This body being capable of being frictionally activated at theworking end or tip of the crayon by the frictional heat generate-d inand on the surface of the adhesive .as it is drawn across the surface ofa firm, dry material, such as a sheet of paper.

This frictional heat at the working tip of the tool or crayon isachieved first from the frictional contact between the working tip ofthe tool and the material upon which it is drawn, and secondly, by theinternal friction generated within the adhesive itself, as it issuddenly elongated in the direction of stress produced .by the movementof 1the tool across the surface of the contacting mate- 1'13.

This motion of the tool tip across the contacting material thus softensthe material so that it is free to be spun off the contacting point in acontinuous adhesive film. The spinning or stretching of the adhesivecontributing additional frictional heat generated within the adhesiveand further softening the material. It is thus rendered both easier tospin off the tool and easier to effect the transfer from the tool tip tothe contacting surface. This is referred to as mark-off. The material ofthe tool is thus transferred and left in an abnormally tacky andsoftened state.

Several mildly pressure sensitive adhesive crayon-like devices havepreviously been developed, including those made entirely of adhesivewaxes and resinous materials.

In my prior applications, Serial No. 641,855, and Serial No. 718,997there were disclosed solid adhesive wax crayons which utilized a lowmolecular weight polymer of isobutylene to both provide additional tackto a tacky blend of microcrystalline waxes, and also to facilitate itsapplication to a firm surface from the solid state. However, the largeproportions of waxes in the formulations limited their adhesiveness sothat their primary usefulness was in the field of paper toys, such aspaper dolls, where mild or temporary adhesives were all that wasdesired.

In my recent application, Serial No. 45,820, now pend.- ing, it wasdisclosed that more adhesive materials could be successfully substitutedfor part of the wax or waxes in earlier formulations. This was madepossible by using the frictional heat generated by the movement of theadhesive on a firm, dry surface, to cause the adhesive to soften at thepoint of contact and become less cohesive and more adhesive than in theunactivated and unsoftened state. This frictionally activated adhesivewas then in condition to be spun off the body of the crayon by the samemotion of the crayon which produced the frictional heat. Thermoplasticadhesive resins were taught to be especially useful in both increasingthe adhesiveness of the adhesive body, and also in generating frictionalheat when used as described.

It was also disclosed that hydrocarbon polymers, and especially lowmolecular weight polymers of isobutylene, such as the non-solid polymerswith molecular weights of from 1,000 to about 20,000 were useful notonly as an adhesive ingredient, but also that they contributed to thefrictional heat and softening of the material at the working face or tipof the tool or crayon, and to the spinning off of thin, ribbon-likefilms of this softened adhesive.

It was also recognized in the pervious application that small quantitiesof butyl rubber or natural rubber latex had beneficial effects in lowconcentrations, especially in the presence of plasticizing oils.

Various other valuable ingredients and rules for formulatingsatisfactory and useful adhesive bodies were previously known anddisclosed in my last application on this subject.

As now comprehended and claimed, this invention is based upon theability of certain combinations of soft wax, hard resin, and softrubbers to produce at least five cooperating actions within the adhesivecomposition used to manufacture the crayons or adhesive tools describedhere. Table I shows the factors supplied by each type of material.

TABLE I Soft rubber Soft wax 111g Tack (Mild) The soft wax or waxes maybe used in proportions of from about 20% to as high as 75% in specialcases.

The soft waxes plasticize and enhance the tack of the resins, both inthe unactivated state, and especially when frictionally activated withheat. They largely contribute the ability of the crayon to mark-off ortransfer to a surface over which the crayon is drawn. Japan, stearicacid, paraffins and spermaceti are most important for this action. Butprobably the most important contribution of the soft wax is to maintainthe applied film of adhesive in a softened and activated state for aperiod of time. For unless this were done the coating would return to arelatively hard and tackless condition within a few seconds required forthe frictional heat to dissipate.

The soft wax can also contribute directly to the tack of the adhesive.For this purpose microcrystalline waxes with melting points below about180 F. are most useful, with bees wax, Japan, ozokerite, ceresin andhard tallow also useful to lesser degrees.

The hard resins found most suitable for this purpose are brittle at 70F. although they may undergo some cold flow over a period of time. Theprocessed resins are also preferred over unprocessed natural resins,although natural Wood rosin, para-coumarone-indene, dammar and ester gumresins are of some limited value. The hydrogenated terpenes, includingpolymerized terpenes, phenolic terpenes, and polymerized rosin estersand hydrogenated rosins with melting points of approximately 150 F. ormore have been found the most useful.

One or more resins in proportions of from 15% to 75% by weight, may beused to achieve various functions, in the adhesive.

The resin or resins contribute largely to the adhesiveness of thecrayon, control the softening point in combination with the waxes used,contribute greatly to the creation of frictional heat, both at thesurface, and to a lesser degree, to internal friction. Where no specialhardener, such as a hard Wax, is used, the resin determines the overallhardness of the crayon.

The rubber ingredients found to be most generally suited are actuallyhydrocarbon polymers with molecular weights of from about 1,000 to25,000, and in quantities of from about 1% to 35% by weight. However,other rubbers such as butyl or natural latex may be used singly, inplace of, or in combinations with these lower molecular weight polymersin proportion up to about 15 providing that they are sufficientlyplasticized to reduce their nerve or toughness and increase their tack.Soft waxes, especially Japan wax, can plasticize the rubber, but the useof a suitable plasticizing oil is often desirable. Generally theseshould be of a mineral origin, naphthenic and paraffinic oils which arehighly saturated are suitable. These oils will also improve the tack ofthe harder resins, although fatty acid oils of animal or vegetableorigin have a much greater tack producing action on the resinssuggested.

Butyl rubber may be defined as a synthetic rubber-like material which isa copolymer of an olefine and a diolefine, for example, a copolymer of amajor proportion of isobutylene and a minor proportion of a diolefinecopolymerizable therewith, such as, butadiene-l,3, isoprene, 2,3-dimethyl butadiene-1,3, pentadiene-l,3, is referred to in British Patent523,248, and in Industrial and Engineering Chemistry, 32, pages 1283 etseq. (1940).

The rubber ingredient should be of such softness in the crayoncomposition as to tend to spin a film when the adhesive is strokedrapidly across a sheet of paper. While this film spinning action isessentially the function of the rubber, it also generates considerablefrictional heat especially within the film of adhesive as it is drawnoff the crayon. The soft rubber also adds tack, especially incombination with the resin.

All three prime ingredients may be used in more than one form to achievethe desired characteristics. The waxes in particular admitting of manycombinations.

In addition to these three primary and essential ingredients, severaladditional modifying agents have been found useful in formulatingvarious adhesive crayons, especially where a particular characteristicor use is desired.

One of these is the area of hard waxes and related materials. These aregenerally in the group with melting points of from about 180 F. to over200 F. and include oxidized microcrystalline wax, oxidized paraffin,hydrogenated vegetable oils, such as castor oil, carn-auba, montan,candelilla, sugar or rice wax. Various high melting resins, such aspolymerized and phenolic terpenes, alone or with high melting waxes areuseful, as is low molecular weight polyethylene resin. This lattermaterial makes possible adhesive films that have a relatively cleanpeeling property.

The use of plasticizing oils has already been mentioned in thediscussion of softening high molecular Weight rubbers, and in increasingthe tack of higher melting point resins.

Another additive that is considered essential for any crayon whereprolonged holding properties are essential, is in the area of oxidationinhibitors.

Because rubbers, resins, and most waxes and oils are subject todeterioration through oxidation, and especially so when spread out inthin films on porous materials, such as paper, the use of stabilizingchemicals is most desirable.

Many excellent oxidation inhibitors are widely available under a varietyof trade names, and suited to this use. One such group is the stericallyhindered phenols, such as 2,6-di-tert-butyl-p-cresol or2,6-di-tert-buty1 4 methylphenol. These can be used in proportions offrom about .01% to 1.0% or even higher. The use of an oxidationinhibitor is also valuable in helping to prevent darkening of the moltenadhesive during the compounding and forming operations.

To compare the relative holding power of coatings applied from variousformulations of the present adhesive crayons, and to compare these withprevious compositions it was found necessary to modify previously usedtest procedures.

Smooth vellum cards of about 50 pound stock and three by five inches indimensions were joined in a one square inch area by applying a heavycoating of the test crayon to one card by repeated rapid strokes in anarea slightly more than one square inch, and centrally located to theside edges but near one end of the card. This was immediately coveredwith the opposite end of a duplicate uncoated card and the two pressedtogether at the adhesive location by means of a one kilogram weightresting on a one square inch soft rubber pressure block for five sec--ends at 72 F.

The test sample was then permitted to cure for a measured period ofhours. At the end of the cure period the sample was tested by clampingthe free ends of the cards in a tensiometer, calibrated to 3 kilogramsin 14.5 inches, in increments of grams.

In previous tests, thin films of test crayons were employed to joinpaper strips with a light weight, and the test Was concluded as soon asthe joint was complete. Not only did the thin adhesive coatings giveless consistent results, but they were not indicative of the maximumstrength of the adhesive. Nor did this show the effect of time on thevarious adhesives used.

TABLE II Formula 2 Minutes 2 Hours 12 Hours 24 Hours All readings aregrams per square inch when sealed with one kilogram weight. Softrnicrocrystalline wax has an approximate rating of 150 at all timeintervals shown.

It is a phenomenon of the wax-resin-rubber mixtures which form a basisfor this invention that they remain in a subnormal state of softness fora period of time, ranging from some minutes to many hours, after thecoating has been applied. In many cases the holding strength of jointsincreases greatly in a matter of minutes. Table II shows the relativestrength of some typical formulations of crayons at various timeintervals. It should be pointed out that these are not maximum strengthsfor any formulation, as the strength of joints can be increased by usinghigher joining pressures. In the tests, only approximately 50% of theone square inch test area was actually found to have been joined. Evenwith these joints, however, some formulations increased in strength byas much as 2,000 grams per square inch in two hours curing time,

and reached a maximum of over 3 kilograms in 24 hours 1 or less.

While no calibrated test was devised to indicate the relative ease ofapplication of various formulations of crayons, there is a very widediiference in this ability. The tougher and more cohesive theformulation, the more difficult it is to separate a film of the materialfrom the crayon body. It has been found that the higher the initialstrength of a formulation tested, the more difficult 8 the film ofadhesive will be to separate from the crayon in the manner taught bythis invention.

However, the cured strength of a given adhesive crayon is in no wayindicative of the ease of application.

A related observation is that in two adhesive crayon formulations ofequal cured strength, the formulation with the lower softeningtemperature will apply a film in the manner taught, with less physicaleffort than the formula tion with the higher softening point. For thisreason the softening point of the formulation should be generally keptas low as practical.

It should be mentioned that while the successful application of a filmof adhesive from. the crayon depends upon the hardness differentialbetween the body of the crayon and the film of adhesive at the workingtip of the crayon, it is neither essential nor necessarily desirablethat the body of the crayon be harder than needed to withstand thepressure and stress of application.

RANGE OF //V L-LOW 6' IO 2O TABAE SQFT WAXES 'RUBBERS HARD RESINSOXIDAT'lON INHIBITORS HARD WAXES i o 55 PLASTICIZER L OILS' 0- 10%COLORINGS o -5 TAB LE IV Formula #39 #715 Ingredient:

14 Strength, grams per sq. in., 2 hours Key to Ingredients:

1. lliicrocrystalline Wax F. 2. Microcrystalline wax F.

. Japan wax. Stearie acid.

Paraffin 128 F. Polyethylene 210 F. Polyisobutylene 10,000 m.w. Butylrubber 50,000 m.w.

Oxidized mieroerystalline wax. Phenolic terpene resin 200 F. plus.

Polymerized terpeno resin 115 C. 13. Polymerized terpene resin 70 C; 14.Sterically kindred bisphenol.

. Glyeeryl ester of hydrogenated wood rosin 183 F.

It has been observed that softer formulations generally have a moreprolonged surface tack, and where this quality is desirable, the normalhardness of the cured adhesive should be as low as possible. Thisprolonged tack is also preesnt in formulations which maintain a goodbond on the surface of materials for prolonged periods, in terms ofmonths or years. And this is most true in bonding plastic and metalfilms. A wax penetrometer reading of from about 15 mm. to 45 mm. at 77F. in the cured adhesive is thought to be the ideal range. The range ofingredients is illustrated in Table III with low limits being designatedas L, the high limits designated as H and the preferred proportions ofingredients being approximated as P in the table.

Table IV illustrates several formulations having one or more distinctivecharacteristics considered to be useful under various conditions. Itwill be noted that several of the formulations approximate the preferredbalance of the three essential elements, but do not necessarily use thesame quantities of each individual ingredient.

As with most wax formulations, it is advisable to start the formulationwith the highest melting point ingredients, which are usually theresins. It is also advisable to mill the rubber into the mineral wax andadd any plasticizer needed to soften the rubber, before attempting tocombine these ingredients into the balance of the formulation. Oxi'dation inhibitor should be added to both the rubber-wax mixture and tothe resins at the start of the mixing and melting down operations toavoid deterioration of these ingredients. A steam jacketed wax kettlewith power driven mixing blades is highly desirable for the propermelting and thorough mixing of ingredients. The low melting point waxes,especially vegetable waxes, such as Japan, are most easily damaged byexcessive heat, so should be added last, with the kettle heat turnedoff. The batch should then be poured out in shallow molds or thin slabs,as soon as the mixing is complete, so as to avoid holding the mixture inthe molten state any longer than necessary.

It is, of course, possible to pour the freshly formulated adhesive intoits final form while still molten. To do this it is suggested thatporous molds, such as plaster of Paris, or wood be used, and that theinterior surfaces be moistened with glycerine to prevent the adhesivefrom sticking to the mold.

The stick may be of any convenient cross-sectional diameter and shape,and may be as thin as one quarter inch in diameter, while for variousheavy duty applications a stick an inch or more in diameter is useful.Generally it has been found that a cylindrical stick of about inch toinch is desirable. Where the body of the crayon or applicator iscylindrical or rod shaped it is preferably circumferentially enclosedwithin a sheath 11 of metallic foil or plastic. The body 10 shouldprotrude slightly from the sheath 11 and may be made with a variety ofshapes to provide the important working tip. Variously shaped workingtips are illustrated as 12, 17, 18, 19, 20, and 21. The precise shape isnot material so long as there is a convex or pointed area from which toapply the adhesive. Actually the use of the applicator or crayon willconstantly change the profile and general shape with wear, but as thesuccessful application always depends to some degree upon frictionalheat, a working tip of limited area will provide the concentration of.frictional heat needed.

It is practical to pour the molten adhesive directly into the sheath 11to form a stick of FIG. 1. Tubes of foil are shaped and stood in woodenor plaster forms with the lower end fitting snugly in holes in thematerial. These recesses should be shaped to mold the working tip 12 andshould be treated with a coat of glycerine to prevent the adhesive fromsticking. The tubes are then filled with molten adhesive and the cap 14inserted in the partly cooled body 10 so that the tang 15 will besecurely embedded. If the cap 14 is made of hard wood or plastic it willprovide a convenient blade 16 to seal joints with minimum effort.

To avoid holding the adhesive in the molten state for long periods,however, as well as to reduce the cost of production, it is suggestedthat the material be extruded from a crayon extruding machine. This willnormally only require that the adhesive be warmed to a soft state, fromwhich it can be extruded quite rapidly. If this extruded shape is thencooled in a water bath to about 40 F. it may be readily cut into shortlengths and wrapped in paper or other material while still cold andmoist. Shapes such as shown in FIG. 4 and FIG. 5 are well suited toextrusion.

Shapes such as those shown in FIG. 3, FIG. 6 and FIG. 8 may be molded inwooden or plaster molds coated with glycerine.

While there is no one formulation of these adhesive crayons which can beconsidered ideal for all purposes, there are numerous characteristicswhich are generally desirable in an adhesive of this type. It shouldapply smoothly and with little physical effort, should apply a highlytacky coating which maintains its tack for a prolonged period afterapplication. It should form a firm bond with paper and most other typesof material, and its bonding strength should improve rapidly and sustaina high level of bonding strength for a prolonged period.

A formulation of this type, which admits of numerous minor variations,and is suggested for general use with paper, consists of the followingparts by weight: 10 parts polyisobutylene 10,000 molecular weigh-t; 10parts microcrystalline Wax melting at F. to F.; 15 parts glyceral esterof hydrogenated wood rosin melting at about 183 F.; 15 parts polymerizedterpene resin melting at about 115 C.; 8 parts Japan wax; and .5 partsterically hindered bisphenol antioxidant.

This is designated as Formula 998 in the tables. It may be made firmerby using the higher melting point microcrystalline wax. To make it applymore freely paraffin may be added or substituted for themicrocrystalline or for part of it. Additional Japan wax will give awetter acting adhesive, while the addition of more of the hard resinswill harden the adhesive, raise the melting point, and give adhesivefilms with less tendency to transfer to a second surface.

As with every other adhesive known, it is essential for good resultsthat these adhesives be selected and used with due consideration fortheir capabilities and limitations.

Because the cohesive strength of these adhesives must be within certainlimits if the material is to be separated from the body of the adhesiveas a film or coating, their principle uses must be considered to be of atemporary or semi-permanent nature. However, in the field of paperadhesives they are generally as strong as the surface fibers of thepaper, so that when properly applied and joined, may be used as apermanent adhesive.

If, for example, it is desired to mount newspaper clippings into analbum, this can be readily accomplished without encountering many of theproblems often associated with this task. I

The clipping should be placed on a smooth table top with the reverseside of the clipping uppermost, and while it has a surplus border ofpaper beyond the actual material to be mounted. The clipping is thenheld firmly to the table with the fingers of the left hand near thecenter. If an adhesive tool of this invention is thenheld in the righthand with the thumb and fingers grasping it near the exposed tip orapplying end, and it is stroked rapidly onto the paper in short strokeswhich start near the fingers fo the left hand and move away towards theedges of the paper, lifting the tip free of the paper before terminatingeach stroke, the paper may be easily and rapidly coated with a thintacky film of adhesive.

This coating operation may be accomplished at a leisurely pace, forthere is no need for haste, as with wet adhesives. When the back of theclipping has been largely coated with radial strokes of about one eighthof an inch in width, the clipping will be sufficiently coated to holdsecurely to most papers. Should greater adhesiveness be desired, it isonly necessary to build up a heavier coating of adhesive with additionalstrokes, or if a less permanent bond is desired, the coating need onlybe abbreviated. At this point the clipping may be trimmed to thefinished size without serious inconvenience from the adhesive coating,and thus bringing the adhesive to the extreme outter edges of theclipping without the slightest possibility of the adhesive smearing overto the face.

When the coating and trimming have been completed, it is only necessaryto position the clipping on the page and press it firmly into place.Here again, unlike conventional adhesives, the degree of bond is subjectto variation, simply by varying the bonding pressure.

It should also be noted that the clipping may be placed in limitlesstrial positions without smearing or otherwise defacing the surface onwhich it is laid, as no appreciable transfer or adhesive will occur, asis common with liquid adhesives. Nor will the adhesive grab or seize tothe page, as with various rubber cements, which are applied to bothsurfaces to be joined.

When the clipping is thought to be properly placed it may be lightlypressed down, in which case its will adhere but lightly, and may easilybe removed again without damage.

For maximum mounting strength it is advisable to lay a sheet ofprotective paper over the clipping and rub over the protective sheetwith a hard object, such as the special cap 14 of FIGURE 1.

Should it ever be desired to remove the clipping, it is only necessaryto soften the adhesive by exposing it to moderate heat, such as anelectric hair dryer, or an electric light bulb, and the softened jointmay be readily separated again without damage to either paper.

Where it is desirable to remove traces of the adhesive from paper it isonly necessary to rub the spot briskly with a soft rubber eraser of thetype referred to as art gum. This type of eraser creates sufiicientfrictional heat to soften the film of adhesive and at the same time towork into it crumbs of the eraser. This action soon reaches the pointwhere the adhesive no longer can adhere to the paper and it can bebrushed away. On most other types of material the adhesive may berapidly wiped away with a cloth moistened in a hydrocarbon solvent suchas solvent naphtha.

Several other valuable techniques for applying and using these adhesivecrayons have been found, such as that of applying and using thismaterial in extra thick and tacky coatings to one or more local areas.This is done by rubbing the adhesive crayon rapidly and repeatedly on asmall spot. This action resembles that of erasing a small stubborn inkspot from a piece of paper. If the adhesive crayon is applied in thismanner to an area an inch or less in length, the adhesive will quiteabruptly become semi-fluid under the crayon tip and will apply in athick tacky state.

If such tacky spots are applied near the corners on the reverse side ofsmall photographs they will hold the pictures securely enough for mostphotographic album mounting requirements. The mounting is not visible,does not curl the photograph adheres instantly, yet can be mounted in aleisurely manner, may be repositioned if desired, and may be removedagain at any later time without damage to the album or picture.

In many cases it has been found that small lumps of the adhesive form abetter bond than the thin films previously described.

A very convenient method of applying small dabs of the activatedadhesive directly from the crayon is to press the side of the crayon tipto the surface so that it is held at about a 45 angle to the surface,with the thumb and fingers grasping the stick close to -the contactingend. From this position the wrist is rotated to turn the stick about oneeighth of a turn, while at a fixed position on the contacting surface.This movement is concluded by moving the adhesive crayon laterallyacross the surface to which it is being applied, for a short distance,and finally lifting the tip free of the surface. These combinedmovements leave a small dab of the activated adhesive about one halfinch long, and terminating in a pointed or feathery edge where theapplied adhesive separates from the tool. By repeating this movement anumber of dabs may be quickly spaced across an area. Such dabs areespecially useful in bonding non-flexible materials and objects togetherwhere the contacting surfaces would be too limited to form a good bondif the thinner adhesives films were employed.

One use for these adhesive dabs is in temporarily holding small items ofhardware for trial placement, or in precise locations for making pilotscrew holes or the like. For example, properly positioning the strikerplate of a conventional door catch becomes a very simple operation if itis adhered to the door jam with dabs from this adhesive crayon and movedto the proper location. Once the proper position is found it may then bemarked on the wood with a pencil or scribe and the proper area cut away.Without this technique such a task can be most exacting and timeconsuming. Many variation of this useful expedient are possible.

Numerous uses have been found for such an adhesive crayon in the homerepair and hobby fields, including the holding of templates, gaskets,and shims in place during assembly. Or such dabs will hold nails, screwsor machine nuts to the tool where manual holding would be difficult orimpossible. Even sheet abrasives may be held to either a sanding blockor even the bare hand by means of adhesive from these crayons.

A piece of paper coated with adhesive stroked on from one of thesecrayons will remove lint and hair from clothing, rugs or upholstry, orit will provide a much improved grip when turning off tight screw lidsand caps from jars or bottles.

The adhesive is useful in sealing down scuffed shoe leather or providingshoe laces with a non-slipping knot. Or, it will quickly and easily joinfilm leaders to camera Winding spools.

In the kitchen, these adhesive devices will provide both temporary andpermanent food labels, reseal packages with paper, foil or plasticfilms, mount shelf papers, menus or other papers.

In offices many uses will suggest themselves in connection with thehandling of papers, such as temporarily mounting labels for easy typingand handling, sealing poorly gummed envelopes, overmoistened stamps,posting bulletins, joining papers for files, or enclosure tocorrespondence.

In school, possible uses for these adhesive crayons range fromnon-spilling adhesives for young art students to installing book covers,holding tracing papers, and making movable charts and graphs or othervisual aids.

Among the many uses of these adhesives for play and recreation are theclothing of paper dolls, joining of takeapart toys, construction sets,making decorations, greeting cards and the like, and providing a tackysurface for various game boards to convert them for travel use.

In the industrial field adhesive coatings from these crayons will helpprevent shipping cartons from shifting during transit.

One of the most unique uses for these adhesive crayons is to provide anadhesive path for the wheel of a glass cutter so that the wheel willrotate uniformly in its movernent across the sheet of glass and thusscore the glass with unprecedented uniformity and certainty.

In many of these and other uses it will be seen that highly adhesive,liquid or permanent adhesives would be less desirable or oftenunsuitable, whereas the moderately 13 tacky adhesive from these crayonsserve the purpose well.

I claim as my invention:

1. An adhesive applicator crayon consisting essentially of a ductile,homogeneous body of a thermoplastic pressure sensitive adhesive havingthe characteristics of becoming softer and less cohesive at the area ofcontact and under the influence of the frictonal heat generated when asmall exposed area of the said body is drawn rapidly in frictionalcontact with a smooth, dry, paperlike surface, and then being capable oftransferring a thin, smooth layer of the softened adhesive to the saiddry surface, and the said smooth layer of adhesive remaining in asoftened state for a period of time thereafter, the said body beingcomposed essentially of from 20% to 75% of a soft wax, of from 1% to 35%of a soft rubber, and from 15% to 75% of a hard resin.

2. An article of claim 1 in which the said body is composed of a waxfrom the group consisting of Japan, stearic acid, paraffin, spermaceti,microcrystalline, bees, ozokerite, ceresin, and hard tallow; of a rubbermaterial taken from the group consisting of polyisobutylenes with amolecular weight of from about 1,000 to 25,000, plasticized naturalrubber, plasticized butyl rubber; and a hard resin taken from the groupconsisting of wood rosin, paracoumarone-indene, dammar, ester gum,hydrogenated terpene, polymerized terpene, phenolic terpene, polymerizedrosin ester, hydrogenerated rosin, and hydrogenated rosin ester.

References Cited by the Examiner UNITED STATES PATENTS 990,354 4/1911Harrington 161234 2,142,039 12/1938 Abrams et a1. 161-235 2,380,1267/1945 Sturm 161234 2,524,076 10/1950 Petronio 161202 2,560,916 7/1951Barnhart et al. 161-235 FOREIGN PATENTS 692,945 6/1953 Great Britain.

EARL M. BERGERT, Primary Examiner.

1. AN ADHESIVE APPLICATOR CRAYON CONSISTING ESSENTIALLY OF A DUCTILE,HOMOGENEOUS BODY OF A THERMOPLASTIC PRESSURE SENSITIVE ADHESIVE HAVINGTHE CHARACTERISTICS OF BECOMING SOFTER AND LESS COHESIVE AT THE AREA OFCONTACT AND UNDER THE INFLUENCE OF THE FRICTIONAL HEAT GENERATED WHEN ASMALL EXPOSED AREA OF THE SAID BODY IS DRAWN RAPIDLY IN FRICTIONALCONTACT WITH A SMOOTH, DRY, PAPERLIKE SURFACE, AND THEN BEING CAPABLE OFTRANSFERRING A THIN, SMOOTH LAYER OF THE SOFTENED ADHESIVE TO THE SAIDDRY SURFACE, AND THE SAID SMOOTH LAYER OF ADHESIVE REMAINING IN ASOFTENED STATE OF A PERIOD OF TIME THEREAFTER, THE SAID BODY BEINGCOMPOSED ESSENTIALLY OF FROM 20% TO 75% OF A SOFT WAX, OF FROM 1% TO 35%OF A SOFT RUBBER, AND FROM 15% TO 75% OF A HARD RESIN.